1. Field of the Invention
The present invention relates to an ink-droplet ejecting apparatus of an ink-jet type.
2. Description of the Related Art
In hitherto known ink-jet printers, which are ink-droplet ejecting apparatuses, an ink-jet head is used which ejects an ink droplet from a nozzle by changing a volume of a pressure chamber in which an ink is filled, by displacing an electromechanical transducer (transducer element) such as a piezoelectric element by applying a driving pulse signal.
In the above mentioned ink-jet head, a gradation control in which, a dot diameter is changed is carried out. For forming one dot by a plurality of ink droplets, the driving pulse signal is set such that a plurality of pulses is applied continuously. Moreover, for suppressing an effect on a subsequent ejection of a vibration which is remained (residual vibration) in the ink after the ink droplets are ejected, a stabilizing pulse (canceling pulse) is output after a main pulse for ejecting the ink. For example, an ink jetting apparatus described in U.S. Pat. No. 6,412,923 (corresponds to Japanese Patent Application Laid-open No. 2001-18388), for forming one dot, outputs one after another, an ejecting pulse for a first droplet (a first-droplet ejecting pulse), an ejecting pulse for a second droplet (a second-droplet ejecting pulse), a stabilizing pulse, an ejecting pulse for a third droplet (a third-droplet ejecting pulse), an ejecting pulse for a fourth droplet (a fourth-droplet ejecting pulse), and another stabilizing pulse, and drives these pulses as one set.
Incidentally, in recent years, speed up of a recording speed (high-speed recording) in the ink-jet printers has been sought. For speed up the recording speed, it is necessary to increase a drive frequency, or in other words, to shorten a driving cycle for forming one dot. When the stabilizing pulse is output not only in between the plurality of ejecting pulses, but also at an end as in the ink jetting apparatus described in U.S. Pat. No. 6,412,923, an overall pulse width (width of all pulses) made of a plurality of pulse signals becomes long. As a result, the driving cycle becomes long, and it is not possible to increase the recording speed.